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Ch. 17 Atmosphere and Air Pollution
Rules/Regulations
http://streaming.factsonfile.com/PortalPlaylists.aspx?aid=17963&xtid=35562&loid=31344
New York City – Congestion pricing??
The atmosphere’s composition
Composition
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ThermosphereUp to 500km (300 mi)High temp – would feel cold
Mesosphere50-80km (31-56mi)Low pressure, temp. drops
Stratosphere 11-50 km (7-31 mi)Drier/less denseTemp. increases with altitude due to O3 (17-30kim or 10-19 mi)
TroposphereAvg. thickness 11km (7 mi)WeatherTemperature/density decline with altitude
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Atmospheric Pressure=force per unit area produced by a column of air
Sea Level = 1013 mb (14.7 lb/in2 )
29035 ft (Everest top)= 300mb
Atmospheric properties
• Relative humidity = the ratio of water vapor a given volume of air contains to the amount it could contain at a given temperature. Expressed as percent
• Temperature = average kinetic energy in molecules
• Thermometer = molecular speedometer
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• Equator – Angle of incident radiation perpendicular, greatest concentration of energy
• Poles – Angle of incident radiation obtuse, less concentrated
***The troposphere is warmed primarily by convection
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Seasons
Weather: local physical properties of the troposphere over short time periods: temp, pressure, cloud cover, wind , humidityClimate: patter of atmospheric conditions found across large geographic regions over long periods of time
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Convective Circulation
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• Air Pollutants removed by:– Precipitation– mixing
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Mixing removes pollutants
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Pollutants trapped
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Large scale convective cells determine global patterns of humidity and aridity
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Coriolis Effect – apparent deflection of air from straight path as globe moves beneath
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Outdoor Air Pollution(Ambient)
Natural Sources:
Dust StormsCarry fungal and bacterial spores
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Volcanoes:Particulates including ash, aerosols of SO2 can cool atmosphere
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Fires:Particulates and gases
Types of outdoor air pollution
• Point Sources = specific spots where large quantities of pollutants are discharged (power plants and factories)
• Nonpoint Sources = more diffuse, consisting of many small sources (automobiles)
• Primary Pollutants = directly harmful ,and can react to form other harmful substances
• Secondary Pollutants = form when primary pollutants interact with components of the atmosphere
Anthropogenic Sources
Primary PollutantsPrimary Pollutants
StationaryStationaryMobileMobile
SourcesSourcesNaturalNatural
Most Most hydrocarbonshydrocarbons
Most suspendedMost suspendedparticlesparticles
SOSO22 NONO NONO22
COCO COCO22 Secondary PollutantsSecondary Pollutants
SOSO33
HNOHNO33HH22SOSO44
HH22OO22OO33 PANsPANs
MostMost NONO33––
SOSO4422 –– saltssalts
Successful legislation• Clean Air Act of 1970– standards for air quality– limits on emissions– funds for pollution-control research – Allows citizens to sue parties violating the
standards
• The Clean Air Act of 1990– Strengthens standards for auto emissions, toxic
air pollutants, acidic deposition, stratospheric ozone depletion
– Introduced emissions trading for SO2
6 Criteria Pollutants
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What is the good news????
Air pollution has decreased since 1970
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Remove up to 90% particulates and SO2
Reasons for the decline in U.S. pollution
• Cleaner-burning vehicles and catalytic converters decrease carbon monoxide
• Permit-trading programs and clean coal technologies reduce SO2 emissions
• Scrubbers = technologies that chemically convert or physically remove pollutants before they leave the smokestacks
• Phaseout of leaded gasoline• Improved technologies and
federal policies
• 17.16
Industrial smog Photochemical smog
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Photochemical Smog
Photochemical (brown air) smog
• Produced by a series of reactions– Hot, sunny cities
surrounded by mountains– Light-driven reactions of
primary pollutants and normal atmospheric compounds
– Morning traffic exhaust releases pollutants
– Irritant – eyes, throat, nose– decreased due to emissions
testing
Photochemical Smog
1. 2NO+ O2 2NO2 2. NO2 + UV NO + O3. O2 + O O3
Typical Daily Patterns
Air Quality Guide for Ozone
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Stratospheric Ozone
The hole in the ozone
• Ozone hole = ozone levels over Antarctica had declined by 40-60% – Depletion also in the Arctic and globally– Causes skin cancer, harms crops and
decreases ocean productivity
The Montreal Protocol addressed ozone depletion• Montreal Protocol = 180 nations agreed to cut CFC production in half
– Follow-up agreements deepened cuts
– ozone-depleting chemicals has decreased 95%
– The ozone layer is beginning to recover
– Success story
• included industry
• adaptive management strategy
– Model for international cooperation
Sources of acid deposition
• Originates from burning fossil fuels that release sulfur dioxide and nitrogen oxides– These compounds react with water to form sulfuric
and nitric acids
Acid Deposition
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Acid deposition has not been greatly reduced
• Scrubbers have helped
• SO2 emissions are lower (cap and trade)
• But, NOx emissions are higher
Acid Deposition not Greatly Reduced
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Indoor Air Quality
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